Chemical Whales

TRANSCRIPT

Narration: Of all the continents, Antarctica is the coldest, the driest, the highest, the windiest, and the brightest. And as the only landmass with hardly any people, you’d expect that it’s also the cleanest. For the southern hemisphere’s population of humpback whales to remain healthy, Antarctica needs to be free of chemical pollution.

Dr Susan Bengtson Nash: The main concern is the diffuse sort of toxic effect it has in just compromising the immune system and therefore making the humpback whales more vulnerable to fighting disease.

Narration: But new research is revealing that humpback whales are contaminated by toxins that can only come from their staple diet of krill. In terms of biomass, the Antarctic krill is arguably the most successful animal species on the planet. A few years ago, Susan Bengtson-Nash analysed several thousand of them to see what they might contain.

Dr Nash: We started with krill – krill being the keystone species of the Antarctic, meaning that if you removed the krill, you’re also effectively removing other species. And so it made sense to really start with krill, find out what’s in krill, and thereby you can see what the predators are exposed to as well.

Narration: She found more than a hundred different forms of chemicals known as persistent organic pollutants, or POPs for short. They’re organochlorine pesticides like DDT, or industrial chemicals like PCBs and dioxins. Many were banned decades ago, but are so long-lived they continue to persist today. The problem is that persistent organic pollutants aren’t broken down by water. Instead they dissolve in the body fat of animals.

Dr Nash: They’re very lipophilic, they’re fat loving. So if they do make it into the food web, they can accumulate in our body.

Narration: But how do these synthetic chemicals end up in remote Antarctica, far away from agriculture and industry?

Mark: Let’s say we dump a load of DDT onto our imaginary world here. It’s a long-lived and volatile chemical, so over decades it evaporates into the atmosphere; And it only comes back down again when it hits a colder temperature, and condenses out of the air. That’s how these chemicals move around the world, bouncing from a warm climate to a colder one. And of course, once they get down here, it’s a one-way trip, there’s no going back.

Narration: That’s why persistent organic pollutants end up concentrating at the poles.

Dr Nash: Assuming that an air mass has just deposited some DDT out of the atmosphere onto the ice perhaps, then in the summer when the ice melts, it’ll either be taken up by herbivores such as the krill, or else deposit to the seabed.

Mark: And after krill?

Dr Nash: After krill you’ve got everything else in the Antarctic. Pretty much everything depends directly or indirectly on the krill.

Narration: In the feeding areas around Antarctica, each humpback whale gulps two tonnes of krill every day. As winter sets in, they head north from the ice cap, travelling to warmer waters to give birth and mate. One migration route tracks along the east coast of Australia on the way to North Queensland. This is the humpback highway off North Stradbroke Island, where more than 8000 whales pass every year.

Mark: Here he is. Look at this. A humpback whale, in the middle of its journey from Antarctica up here and all the way back down again. That’s fantastic. It takes seven months, that journey. This is really exciting. Here it comes again. It’s the longest migration, one of the longest migrations, of any mammal. But what amazes me most is that they do it all on an empty stomach. They rely entirely on their fat reserves.

Narration: Susan and her colleague Courtney are the first to investigate the chemical burden in humpbacks as they swim ten thousand kilometres without eating.

Courtney Waugh: Somewhere between about four to eleven kilometres an hour they, they tend to be travelling.

Narration: They aim to get thirty samples of blubber and the chemicals inside – at a time when the whales are most vulnerable to any toxic effects.

Dr Nash: They’re just drawing on their fat reserves that they’ve built up in the summer and with that mobilization of fat you’re going to get mobilization of these contaminants. So all these contaminants that may have been locked away and dormant, are now circulating in the bloodstream and can reach their target sites of toxicity.

Narration: It takes a fair bit of skill, a lot of luck, and a specialised dart gun to take a small plug of blubber from the heaving flank of a speeding whale.

Dr Nash: Court, let’s shoot on the right cos of the lighting.

Courtney: You can often see them under the water just before they surface, so you’ve got quite a lot of time to line up the shot.

Narration: The biopsy darts cause no harm to the humpbacks, unlike the research methods of Japanese whalers.

Dr Nash: And the biopsy dart, don’t forget the diameter of it is the same as some human biopsies, and you look at that in a fifteen metre humpback whale, it’s not really that intrusive.

Courtney: We’ve got a whale ahead. Yep about a hundred metres just in front of the boat. Two whales.

Narration: While Susan and Courtney target the top of the food chain in sunny Queensland down in Hobart, another member of their team tests krill in a refrigerated shipping container.

Mark: Catalyst calling…

Anita Poulsen: Hello Mark, welcome to my little lab…

Narration: Environmental toxicologist Anita Poulsen works in a constant temperature of zero degrees.

Mark: Like a little slice of Antarctica…

Anita: Yeah you could say that.

Mark: What are you doing with the krill here?

Anita: I’m looking at DDE, DDE is the most stable metabolite, breakdown product of DDT, and it is still in use in some countries. This is an algae solution that I’ve contaminated with DDE. I’ll add this to the beakers, and the krill will be feeding on the algae as they would do in the wild.

Narration: DDE is a major contaminant that builds up in wild krill over their lifetime of six years or more. To measure that toxic effect in the lab, Anita simulates the exposure with high doses over a short time.

Anita: We find DDE in an average concentration of two to four nanograms per gram, or two to four parts per billion.

Mark: That doesn’t sound like much.

Anita: No, it’s not a lot, but it is comparable to levels that we see in the Arctic.

Narration: Organochlorines like DDE are carcinogenic neurotoxins that alter how animals move, and disrupt their reproduction.

Anita: Well let’s have a look. What do you think?

Mark: Well, there’s much less activity than there was before.

Anita: Yeah, and you can see that we’ve got at least three out of five krill that are very dark red, they’ve become immobile, sometimes they’ll be doing a few tail flicks.

Narration: It’s evidence that the toxins impair the schooling behaviour of krill, a key feature of their biology.

Mark: If they were exhibiting this kind of behaviour in the wild, what would happen to them?

Anita: That would be a major problem because they are schooling animals, and in the wild it would have dramatic consequences for the survival of the species.

Narration: And in an ecosystem based on billions of tiny krill, all the Antarctic species they support are also at risk…especially the massive whales…

Back on the humpback highway in Queensland, following the toxic trail isn’t easy. First you have to find the right whale.

Mark: Right oh, yep. There’s two.

Courtney: Oh there’s a calf. There’s a calf. Mother and calf. We don’t want a mother and calf, we don’t shoot calves, and we want mainly males.

Narration: Then get close enough to be covered in whale spit. After doing this every day for four weeks, Susan and Courtney are a precision team of gun-toting boaties.

Courtney: Yes! Good shot Susan!

Dr Nash: Keep an eye on the dart, it’s just here… A small plug.

Courtney: Get a plug?

Dr Nash: Yeah a small one.

Mark: Is that the kind of sample you hoped to get?

Dr Nash: Yep, so we can see, this one went in at a bit of an angle. And the skin is quite thick, and then we get a little bit of blubber.

Narration: It’s in the white fat where the contaminants accumulate.

Dr Nash: We just keep thinking what an ambitious thing it is we’re trying to do, you have to get to see the whale, you have to track the whale, then you have to shoot and your equipment has to work and then you have to retrieve the sample. So there’s a lot of things that have to come together.

Narration: They’ve only got one dart left for sampling the northward migration.

Dr Nash: Yeah, so this is field work and then there’s the lab work. (laughs)

Narration: It’s still early days for their research, but preliminary results show the level of DDE in the whales is 18 times greater than in the krill. But the toxic trail doesn’t end there. People are part of the Antarctic food chain too, eating whale meat, or taking krill oil.

No longer can we assume that Antarctica is pristine and clean.

In the whales is a warning that our chemical pollution knows no boundaries.

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Admirer - 11 Jun 2009 6:44:14pm

Dr Nash is a honey.

katie wunsch - 26 Oct 2008 11:52:48am

What a tragerty; makes me want to cry!!!Plaese ABC play this video as much as you can- education of people is the only way we are going to make a differance; we are really at an environmental crisis point.Come on people get back to earth, its the only way we can save our animals & ourselfs!!!!!!